Is It Long Covid? Signs, Timing, and When to See a Doctor

Disclaimer: This article is for educational purposes only and does not replace personalised medical advice, diagnosis, or treatment. Always consult a qualified health professional about your individual situation.

If you are still unwell weeks after a COVID-19 infection, you are not alone – and you are not imagining it. Many people describe lingering, fluctuating symptoms that do not match a simple “slow recovery,” and careful patterns over time often tell us more than any single symptom or test result. 

What is Long Covid?

Long Covid, also called post-COVID-19 condition, describes a set of symptoms that persist or recur after a SARS-CoV-2 infection and cannot be explained by another diagnosis. The WHO definition notes that symptoms usually begin within about three months of the original infection and can last at least two months, while the NHS describes “long-term effects of COVID-19” as symptoms persisting beyond four weeks. 

These post covid symptoms can follow both mild and severe COVID, including cases that never required hospital care. People often move from an acute infection phase (the first days to weeks of fever, cough, and positive tests) into a longer “recovery” phase, where new or ongoing long term covid symptoms may appear.

When Do Long Covid Symptoms Usually Start?

People ask, “Do I have long COVID?” most often when they notice that recovery is not going as expected. Patterns we commonly see include:

• Symptoms that never fully resolve after the initial infection and simply continue beyond 4–12 weeks. 
• Symptoms that seem to improve, then new problems, such as fatigue, brain fog, or palpitations, appear weeks later. 
• Symptoms that come and go, with periods of feeling almost normal followed by relapses or “flares.”
  

These fluctuating, persistent symptoms are a recognised part of post-viral syndrome in post-COVID-19 condition.

Why delayed symptoms can happen

Research suggests that delayed or persistent post covid symptoms may relate to ongoing immune activation, low‑grade inflammation, along with changes in the autonomic nervous system, rather than active acute infection. Studies have described small-vessel and clotting abnormalities, alongside immune dysregulation, which can reduce oxygen delivery to tissues and contribute to fatigue, shortness of breath, and cognitive issues.

If you are curious about the underlying biology, we have prepared a guide that explores these processes in more depth, including microclots and immune imbalance.

Common Signs of Long Covid

Most reported symptoms

Long COVID symptoms can vary from person to person, although several patterns are reported consistently by the NHS and international guidelines: 

• Fatigue that does not improve with rest and limits your normal daily activities. This often feels disproportionate to your level of exertion. 
• Brain fog: problems with memory, concentration, or word-finding that make work or study harder than before. 
• Shortness of breath, especially on exertion, or feeling more “winded” climbing stairs or walking than you used to.
• Chest discomfort or palpitations (a racing, pounding, or irregular heartbeat) without a clear heart diagnosis yet. 
• Muscle or joint pain, headaches, or generalised aches that persist beyond the usual recovery period.
  

These long term covid symptoms can range from mild to disabling, and may shift over time rather than staying the same each day. For a broader overview of symptom clusters and biology, you can read our guide “Long Covid Treatment & Symptoms.” 

Less obvious but commonly missed signs

Some long COVID signs are easy to overlook or mislabel as “just stress” or “getting older”:

• Post‑exertional symptom worsening, which is also known as post‑exertional malaise, or PEM. This can cause symptom flare-ups for hours to days after physical or mental effort, rather than immediately.
• Dizziness on standing, feeling faint, or a racing heart when upright, which may relate to orthostatic intolerance, forms of dysautonomia, or POTS. 
• Heat intolerance, feeling significantly worse in hot weather or after hot showers.
• Sleep issues, such as fragmented sleep, new onset of insomnia, or unrefreshing sleep despite adequate hours in bed.
• Anxiety‑like physical sensations, including palpitations, shortness of breath or shakiness that may reflect autonomic nervous system changes rather than purely psychological causes.
  

Not every person with Long Covid will have all of these symptoms, and recognising the overall pattern is more important than ticking every box.

Symptom patterns to notice

Every day tiredness from a busy week usually improves with a good night’s rest and does not significantly interfere with your basic functions.

Signs that point more towards long COVID symptoms include:

• Symptoms reliably worsen after physical or mental effort, even modest tasks like shopping, reading, or answering emails (post‑exertional malaise).
• “Good days” followed by crashes where you feel significantly more unwell for hours or days afterwards.
• Multiple systems are affected at once, for example, fatigue plus brain fog, sleep disturbance, palpitations, and gut changes, rather than a single isolated complaint.
  

Clinicians sometimes describe this as a systemic or functional impairment affecting whole‑body resilience rather than a simple local problem.

Why “normal tests” don’t always mean nothing is wrong

Many people with post covid symptoms have normal routine blood tests, chest X‑rays, or basic heart tracings. This does not mean your symptoms are imagined; it reflects that standard tests are designed to detect major organ damage, not subtle post-viral or autonomic dysfunction.

Current research shows that long COVID can involve microvascular, immune, and nervous‑system changes that are not captured by everyday laboratory panels. Our article “Why Long Covid Should Be Treated Like a Chronic Condition” discusses why a long‑term, functional view of recovery is often more helpful than expecting rapid “all‑clear” results.

Is It Long Covid or Something Else?

Conditions that can overlap in symptoms

Several other medical conditions can mimic or overlap with long COVID signs:

• Anaemia, which can cause fatigue, breathlessness, and palpitations
• Thyroid conditions which may change energy levels, heart rate, weight, and mood.
• Anxiety or depressive disorders, which can contribute to insomnia, palpitations, and brain fog, sometimes interact with autonomic symptoms.
• Post-viral fatigue or post-viral syndrome from other infections, such as glandular fever, can look clinically similar.
  

Because these conditions may co-exist with post-COVID-19 condition, a careful assessment is important rather than assuming everything is Long Covid.

Why proper assessment still matters

Self-checking can be a helpful first step, but it is not a diagnosis.

A thorough medical assessment allows your doctor to:

• Rule out treatable causes like anaemia, thyroid disease, or cardiac problems.
• Keep an official record of the pattern and impact of persistent symptoms over time.
• Decide whether referral to a Long Covid clinic, rehabilitation service, or specialist is appropriate.
  

Our team at The Apheresis Centre often works alongside local physicians and Long Covid services, building on these initial assessments rather than replacing them.​

When to See a Doctor

Book a GP appointment if you:

You should usually arrange a non‑urgent GP appointment if:

• Symptoms last more than 4–8 weeks after your initial COVID-19 infection, especially if they are not gradually improving.
• Your daily life, work, study, or caring responsibilities are affected by fatigue, brain fog, breathlessness, or other persistent symptoms.
• Symptoms are worsening rather than stabilising or improving over time, or new symptoms keep appearing.
  

If available in your area, your Doctor may refer you to a post-COVID assessment or rehabilitation service for more specialised support.

Seek urgent care if you have:

Some symptoms require same‑day medical attention or emergency care, and these are:

• New or worsening chest pain, especially if it feels heavy, tight, or is associated with sweating, nausea, and/or pain radiating to the arm or jaw.
• Severe breathlessness, including difficulty speaking in full sentences or sudden worsening of existing respiratory symptoms.
• Fainting, a sudden collapse, or feeling as though you will pass out when standing, that does not improve quickly.
• New neurological symptoms such as sudden weakness, difficulty speaking, facial drooping, or seizures.
  

If you’re in doubt, follow local emergency service guidance (for example, NHS 111, emergency departments, or ambulance services in your region).

How to Prepare for your Long Covid Appointment

Making notes before your consultation can be beneficial to both you and your clinician to ensure you make the most of your time together. 

Many patients find it useful to bring:

• A symptom timeline: when your acute COVID started, when you tested positive, and how symptoms have changed since.
• A list of triggers: activity, heat, stress, menstrual cycles, sleep changes, and anything that consistently worsens or improves your symptoms.
• A brief description of functional impact: what you can do on a good day versus a bad day (work, household tasks, social life, exercise).
• Previous COVID dates, test results, and any letters from the hospital or clinics related to your infection or follow‑up.
  

Our comprehensive long Covid therapy resources also outline questions you might wish to ask about investigations and rehabilitation options.​

Common Questions About Long Covid Signs

Can Long Covid start months after infection? 

Symptoms most often begin during or within weeks of the acute infection, but some people report new or recognisable long COVID signs emerging several months later, still within the broad WHO definition window.

Can Long Covid happen after mild COVID?

Yes, many people with post-COVID-19 condition were never hospitalised and initially had what seemed like a mild infection.

How long do Long Covid symptoms usually last?

The duration varies with some individuals improving over a few months, while others report persistent or fluctuating symptoms beyond 12 months. Ongoing medical follow‑up is important so your care plan can adapt to your symptoms over time.

Can children and younger adults get Long Covid?

Long Covid has been diagnosed in children, adolescents, and younger adults, although patterns and prevalence differ by age group. Paediatric assessment is essential when symptoms affect schooling or development.

Does anxiety cause Long Covid symptoms, or the other way around?

Anxiety and low mood can both result from living with unpredictable, disabling symptoms and also amplify physical sensations like palpitations or breathlessness. However, the current evidence indicates that post-COVID-19 condition involves biological changes beyond mental health alone, so this means both physical and psychological aspects deserve attention.

If you recognise these long COVID signs and your daily life is being limited by persistent or fluctuating post covid symptoms, speaking with your GP or local Long COVID service is an important next step forward.

Author / Medical Review Note

Written by Andrew Smith, experienced in managing complex chronic and post-viral conditions. Reviewed by Dr Inbar Tofan, Medical Director at The Apheresis Centre, Cyprus, with over 10 years of experience in internal medicine, therapeutic apheresis, and complex chronic illness care.​

Key References

– Healthdirect Australia. Long COVID. (https://www.healthdirect.gov.au/long-covid)

– National Center for Biotechnology Information (NCBI). Peer-reviewed research article on Long COVID. (https://pmc.ncbi.nlm.nih.gov/articles/PMC11605154/)

– National Institute for Health and Care Excellence (NICE). Managing the long-term effects of COVID-19 (NG188). (https://www.nice.org.uk/guidance/ng188)

– NHS Cheshire and Merseyside. Long COVID.
(https://www.cheshireandmerseyside.nhs.uk/your-health/helping-you-stay-well/long-covid/)

– NHS. Long COVID. (https://www.nhs.uk/conditions/long-covid/)

– NHS North East London Integrated Care Board. Long-term effects of COVID-19 (Long COVID). (https://northeastlondon.icb.nhs.uk/health-advice/long-term-effects-of-covid-19-long-covid/)

– NSW Health. Long COVID – Fact sheet. (https://www.health.nsw.gov.au/Infectious/factsheets/Factsheets/long-covid-english.pdf)– United Nations News. WHO calls for action on long COVID. (https://news.un.org/en/story/2021/10/1102562)